In remote work Spaces, the Participants list divides users into three groups: Members, Guests, and Offline Members. A Member is a user logged into the Space with their Gather account who has been set as a Moderator, Builder, or Owner in that Space. A Guest is anyone visiting the Space who does not have an assigned user role.
If you need to remove someone from the Member list, go to the Space Dashboard and click User Roles. Find their email address under the Owners, Moderators, or Builders section, click it, and click the trashcan to delete.
Tip: If you have a lot of members with user roles, use Ctrl + F to search for their email address.